Learn about this topic in these articles:

association with Maïnassara

Maïnassara, who was of Hausa ancestry, enlisted in the army in 1970 and three years later became aide-de-camp to President
Seyni Kountché. Extremely loyal to the president, Maïnassara was appointed commander of the Presidential Guard in 1976 and in 1978 was given charge of the army’s prestigious airborne regiment. He held a series of overseas posts, including military...

leadership of Niger

After independence was proclaimed, Diori set up a single-party dictatorship and ruled until he was toppled in a coup in 1974. There followed a military dictatorship headed first by
Seyni Kountché (until his death in 1987) and then by Ali Seibou. Mahamane Ousmane of the Social Democratic Convention became president in the country’s first multiparty presidential elections in 1993....

opposition to Diori

...government was unable to relieve a famine in Niger resulting from a drought in the Sahel, and on April 15, 1974, he was overthrown in a coup led by the army chief of staff, Lieutenant Colonel
Seyni Kountché. Diori was imprisoned by the new government from 1974 to 1980 and then held under house arrest until 1987.